Microvascular reconstruction of iatrogenic femoral artery thrombosis in an infant: a case report and review of the literature: infant femoral artery reconstruction

OBJECTIVE

We present a case of femoral artery thrombosis and acute limb ischemia in an infant following attempted femoral venipuncture. Microsurgical reconstruction of the lesion and a review of the literature are described.

METHODS

Insertion of intravascular catheters is a commonly performed procedure in neonatal and pediatric intensive care units. However, significant iatrogenic injuries to the peripheral vascular system can occur. Management ranges from anticoagulation and thrombolytics to surgical intervention. In this case, surgical therapy involved thrombectomy and microsurgical reconstruction of the femoral artery.

RESULTS

Vascular inflow was reestablished and the limb was salvaged.

CONCLUSIONS

We believe that microsurgical techniques are an important component for successful vascular reconstruction after iatrogenic artery thrombosis in an infant. Microvascular techniques allow for a controlled operating field with magnification, thereby assisting in the accuracy of vessel repair.

Bilateral total hip replacement in osteogenesis imperfecta with hyperplastic callus

Osteogenesis imperfecta is a rare inherited disorder of connective tissue which may present with recurrent fractures which are prone to nonunion and malunion resulting in deformity. Some patients develop osteoarthritis of the hip. Formation of hyperplastic callus after recurrent fractures may deform the shape of the femur and preclude the use of standard implants at joint replacement. Replacement can thus be technically demanding.

We present a case of bilateral hip replacement in a patient with osteogenesis imperfecta and hyperplastic callus which was treated by the use of long femoral allografts and cemented femoral stems.

Recurrence analysis of strange nonchaotic dynamics

We present methods to detect the transitions from quasiperiodic to chaotic motion via strange nonchaotic attractors (SNAs). These procedures are based on the time needed by the system to recur to a previously visited state and a quantification of the synchronization of trajectories on SNAs. The applicability of these techniques is demonstrated by detecting the transition to SNAs or the transition from SNAs to chaos in representative quasiperiodically forced discrete maps. The fractalization transition to SNAs--for which most existing diagnostics are inadequate--is clearly detected by recurrence analysis. These methods are robust to additive noise, and thus can be used in analyzing experimental time series.

Data perturbation independent diagnosis and validation of breast cancer subtypes using clustering and patterns

Molecular stratification of disease based on expression levels of sets of genes can help guide therapeutic decisions if such classifications can be shown to be stable against variations in sample source and data perturbation. Classifications inferred from one set of samples in one lab should be able to consistently stratify a different set of samples in another lab. We present a method for assessing such stability and apply it to the breast cancer (BCA) datasets of Sorlie et al. 2003 and Ma et al. 2003. We find that within the now commonly accepted BCA categories identified by Sorlie et al. Luminal A and Basal are robust, but Luminal B and ERBB2+ are not. In particular, 36% of the samples identified as Luminal B and 55% identified as ERBB2+ cannot be assigned an accurate category because the classification is sensitive to data perturbation. We identify a "core cluster" of samples for each category, and from these we determine "patterns" of gene expression that distinguish the core clusters from each other. We find that the best markers for Luminal A and Basal are (ESR1, LIV1, GATA-3) and (CCNE1, LAD1, KRT5), respectively. Pathways enriched in the patterns regulate apoptosis, tissue remodeling and the immune response. We use a different dataset (Ma et al. 2003) to test the accuracy with which samples can be allocated to the four disease subtypes. We find, as expected, that the classification of samples identified as Luminal A and Basal is robust but classification into the other two subtypes is not.

Adaptive targeting of chaotic response in periodically stimulated neural systems

We demonstrate a technique for the enhancement of chaos in a computational model of a periodically stimulated excitable neuron. "Anticontrol" of chaos is achieved through intermittent adaptive intervention, which is based on finite-time Lyapunov exponents measured from the time series. Our results suggest that an adaptive strategy for chaos anticontrol is viable for increasing the complexity in physiological systems that are typically both noisy and nonstationary.

Pencil is mightier than the sword!

Penetrating injuries involving the spinal cord are not common. The incidence is, however, much higher in armed conflict. In a civilian population, gunshot wounds and stabbings account for the majority of such injuries. A pencil causing penetrating injury involving the spinal cord is very rare. We present the case of a young boy who accidentally suffered a penetrating injury involving the spinal cord from a pencil in his coat pocket.

Neurolisteriosis causing hydrocephalus, trapped fourth ventricle, hindbrain herniation and syringomyelia

Central nervous system infection by Listeria monocytogenes is relatively uncommon, but is known to be highly morbid and fatal. We describe a case of listeria meningoencephalitis, wherein the acute episode was followed by a hitherto unreported conglomeration of severe and progressive neurological sequelae, in the form of supratentorial hydrocephalus, aqueduct block, trapped fourth ventricle, hindbrain herniation and syringomyelia. Pertinent literature is reviewed and the pathogenesis of the observed sequelae is explored.

Approach to equilibrium in adiabatically evolving potentials

For a potential function (in one dimension) which evolves from a specified initial form V(i)(x) to a different V(f)(x) asymptotically, we study the evolution, in an overdamped dynamics, of an initial probability density to its final equilibrium. There can be unexpected effects that can arise from the time dependence. We choose a time variation of the form V(x,t) = V(f)(x) + (V(i) - V(f)) e(-lambda t). For a V(f)(x), which is double welled and a V(i)(x) which is simple harmonic, we show that, in particular, if the evolution is adiabatic, this results in a decrease in the Kramers time characteristic of V(f)(x). Thus the time dependence makes diffusion over a barrier more efficient. There can also be interesting resonance effects when V(i)(x) and V(f)(x) are two harmonic potentials displaced with respect to each other that arise from the coincidence of the intrinsic time scale characterizing the potential variation and the Kramers time. Both these features are illustrated through representative examples.

Spectral Repeat Finder (SRF): identification of repetitive sequences using Fourier transformation

MOTIVATION

Repetitive DNA sequences, besides having a variety of regulatory functions, are one of the principal causes of genomic instability. Understanding their origin and evolution is of fundamental importance for genome studies. The identification of repeats and their units helps in deducing the intra-genomic dynamics as an important feature of comparative genomics. A major difficulty in identification of repeats arises from the fact that the repeat units can be either exact or imperfect, in tandem or dispersed, and of unspecified length.

RESULTS

The Spectral Repeat Finder program circumvents these problems by using a discrete Fourier transformation to identify significant periodicities present in a sequence. The specific regions of the sequence that contribute to a given periodicity are located through a sliding window analysis, and an exact search method is then used to find the repetitive units. Efficient and complete detection of repeats is provided together with interactive and detailed visualization of the spectral analysis of input sequence. We demonstrate the utility of our method with various examples that contain previously unannotated repeats. A Web server has been developed for convenient access to the automated program.

AVAILABILITY

The Web server is available at http://www.imtech.res.in/raghava/srf and http://www2.imtech.res.in/raghava/srf

Global optimization on an evolving energy landscape

Locating the global minimum of a complex potential energy surface is facilitated by considering a homotopy, namely, a family of surfaces that interpolate continuously from an arbitrary initial potential to the system under consideration. Different strategies can be used to follow the evolving minima. It is possible to enhance the probability of locating the global minimum through a heuristic choice of interpolation schemes and parameters, and the continuously evolving potential landscape reduces the probability of trapping in local minima. In application to a model problem, finding the ground-state configuration and the energy of rare-gas (Lennard-Jones) atomic clusters, we demonstrate the utility and the efficacy of this method.

Critical states and fractal attractors in fractal tongues: localization in the Harper map

Localized states of Harper's equation correspond to strange nonchaotic attractors in the related Harper mapping. In parameter space, these fractal attractors with nonpositive Lyapunov exponents occur in fractally organized tongue-like regions which emanate from the Cantor set of eigenvalues on the critical line epsilon=1. A topological invariant characterizes wave functions corresponding to energies in the gaps in the spectrum. This permits a unique integer labeling of the gaps and also determines their scaling properties as a function of potential strength.

Isolated buttock burns: epidemiology and management

This is a retrospective study of the epidemiology and management of isolated buttock burns presenting to the Welsh Regional Burns Centre from January 1996 to December 1999. A total of 36 cases have been treated of which 31 are included in this study. Approximately, 50% are in the paediatric age group and the sex distribution is equal for both adults and children. Contact burns form the largest group, and in children resulted in superficial burns requiring dressings only. The adult population is more likely to sustain deeper burns that require skin grafting, and approximately 50% will have a contributing premorbid condition. Despite difficulties in dressing and positioning of the patients, grafting of full thickness burns is appropriate without recourse to faecal diversion.

Vaccum assisted closure: an alternative strategy in the management of degloving injuries of the foot

A case of a degloving injury to the foot is presented in a patient who also sustained severe contralateral lower-limb trauma. We report a technique for salvaging the foot by replacing the degloved skin as a full-thickness graft and securing it using the vacuum-assisted closure (VAC) device. A good outcome was achieved and technical tips are provided to facilitate reproduction of the procedure.

Effects of virologic rebound on CD4 cell counts

A retrospective study was conducted to assess the effects of various degrees of virologic rebound on CD4 cell counts over time in human immunodeficiency virus-infected patients. We found that (1) the higher the degree of virologic rebound, the more rapid the decrease in CD4 cell counts over time, and (2) the magnitude of the virologic rebound was inversely correlated with the CD4 cell counts at the time of rebound.

Noninvasive diagnosis of renal-allograft rejection by measurement of messenger RNA for perforin and granzyme B in urine

BACKGROUND

Acute rejection is a serious and frequent complication of renal transplantation, and its diagnosis is contingent on the invasive procedure of allograft biopsy. A noninvasive diagnostic test for rejection could improve the outcome of transplantation.

METHODS

We obtained 24 urine specimens from 22 renal-allograft recipients with a biopsy-confirmed episode of acute rejection and 127 samples from 63 recipients without evidence of acute rejection. RNA was isolated from the urinary cells. Messenger RNA (mRNA) encoding the cytotoxic proteins perforin and granzyme B and a constitutively expressed cyclophilin B gene were measured with the use of a competitive, quantitative polymerase chain reaction, and the level of expression was correlated with allograft status.

RESULTS

The log-transformed mean (+/-SE) levels of perforin mRNA and granzyme B mRNA, which encode cytotoxic proteins, but not the levels of constitutively expressed cyclophiiin B mRNA, were higher in the urinary cells from the 22 patients with a biopsy-confirmed episode of acute rejection than in the 63 recipients without an episode of acute rejection (perforin, 1.4+/-0.3 vs. -0.6+/-0.2 fg per microgram of total RNA; P<0.001; and granzyme B, 1.2+/-0.3 vs. -0.9+/-0.2 fg per microgram of total RNA; P<0.001). Analysis involving the receiver-operating-characteristic curve demonstrated that acute rejection can be predicted with a sensitivity of 83 percent and a specificity of 83 percent with the use of a cutoff value of 0.9 fg of perforin mRNA per microgram of total RNA, and with a sensitivity of 79 percent and a specificity of 77 percent with the use of a cutoff value of 0.4 fg of granzyme B mRNA per microgram of total RNA. Sequential urine samples were obtained from 37 patients during the first nine days after transplantation; and measurements of the levels of mRNA that encoded cytotoxic proteins identified those in whom acute rejection developed.

CONCLUSIONS

Measurement of mRNA encoding cytotoxic proteins in urinary cells offers a noninvasive means of diagnosing acute rejection of renal allografts.

Intermittency transitions to strange nonchaotic attractors in a quasiperiodically driven duffing oscillator

Different mechanisms for the creation of strange nonchaotic attractors (SNAs) are studied in a two-frequency parametrically driven Duffing oscillator. We focus on intermittency transitions in particular, and show that SNAs in this system are created through quasiperiodic saddle-node bifurcations (type-I intermittency) as well as through a quasiperiodic subharmonic bifurcation (type-III intermittency). The intermittent attractors are characterized via a number of Lyapunov measures including the behavior of the largest nontrivial Lyapunov exponent and its variance, as well as through distributions of finite-time Lyapunov exponents. These attractors are ubiquitous in quasiperiodically driven systems; the regions of occurrence of various SNAs are identified in a phase diagram of the Duffing system.

Identification of parasitic genes by computational methods

A number of parasite genome projects are under way, and large amounts of nucleotide sequence data are becoming available for analysis. There is an urgent need for development of theoretical tools to analyze the genome data, including identification of protein-coding sequences. The majority of the methods developed to date require prior information about the genome before accurate predictions can be made. Because such information is not available for many parasites, these methods cannot be directly applied. In this article, Alok Bhattacharya and colleagues describe some of the gene-prediction methods commonly in use, and a new method, GeneScan, that they have developed for the analysis of parasite genomes.

Dynamics of a shallow fluidized bed

The results of the experimental study of the dynamics of a shallow fluidized bed are reported. The behavior of granular material is controlled by the interplay of two factors--levitation due to the upward airflow, and sliding back due to gravity. Near the threshold of instability, the system shows critical behavior with remarkably long transient dynamics. The experimental observations are compared with a simple cellular automata model.

Characteristic distributions of finite-time Lyapunov exponents

We study the probability densities of finite-time or local Lyapunov exponents in low-dimensional chaotic systems. While the multifractal formalism describes how these densities behave in the asymptotic or long-time limit, there are significant finite-size corrections, which are coordinate dependent. Depending on the nature of the dynamical state, the distribution of local Lyapunov exponents has a characteristic shape. For intermittent dynamics, and at crises, dynamical correlations lead to distributions with stretched exponential tails, while for fully developed chaos the probability density has a cusp. Exact results are presented for the logistic map, x-->4x(1-x). At intermittency the density is markedly asymmetric, while for "typical" chaos, it is known that the central limit theorem obtains and a Gaussian density results. Local analysis provides information on the variation of predictability on dynamical attractors. These densities, which are used to characterize the nonuniform spatial organization on chaotic attractors, are robust to noise and can, therefore, be measured from experimental data.

Effects of cyclic AMP on expression of myelin genes in the N20.1 oligodendroglial cell line

The N20.1 immortalized cell line has several characteristics of differentiating oligodendrocytes (OLs), including expression of the glycolipids galactocerebroside (GalC) and sulfatide, and the myelin proteins CNPase and myelin basic protein (MBP) (1,2). Addition of 1-100 microM forskolin to elevate cyclic AMP (cAMP) levels changed cell morphology from irregular and flattened to a more rounded birefringent cell with multiple branched processes. GalC and sulfatide were detected immunocytochemically after permeabilization in the untreated cells and levels appeared to increase slightly following exposure to forskolin. Further analysis showed that most of the glycolipid was internal, with virtually no detectable levels on the cell surface in untreated cells and a very slight change following treatment with forskolin. Synthesis of the two lipids as measured by [H3]galactose incorporation doubled within 24 hours of treatment with forskolin. Levels of message for UDP-galactose: ceramide galactosyl transferase (CGT), a key enzyme in the synthesis of GalC and sulfatide, were compared with those of MBP and proteolipid protein (PLP), before and after elevation of cAMP. No changes were observed in levels of mRNA for CGT and PLP after 24 hours, with a possible increase by 48 hours. In contrast, levels of MBP message dropped precipitously by 24 hours; this was accompanied by an increase in levels of message for suppressed cAMP-inducible POU (SCIP). Thus CGT transcription is regulated independently of MBP and SCIP in N20.1 cells. Analysis of MBP levels by immunocytochemistry and Western blot showed little or no change in protein levels at 24 and 48 hours, in contrast to the sharp decrease in message levels by 24 hours, indicating a relatively long half life for MBP in this cell line. Thus, the N20.1 cells are an informative model for examining regulation of expression of myelinotypic proteins and GalC, as well as the transport of this lipid to the plasma membrane.

Application of rank analysis of covariance methods to analysis of multiple anatomical regions with treatment for seborrheic dermatitis

This paper presents the advantages of rank analysis of covariance in contrast to the Mantel-Haenszel procedure in the presence of a covariate. In this paper, data from a clinical trial with an indication for seborrheic dermatitis, which afflicts multiple anatomical regions, is presented. This paper presents analysis performed using both the Mantel-Haenszel procedure and rank analysis of covariance for separate anatomical regions, as well as for the combined anatomical regions. The analysis for the combined anatomical regions involves weighted sums over different strata.

Prediction of probable genes by Fourier analysis of genomic sequences

MOTIVATION

The major signal in coding regions of genomic sequences is a three-base periodicity. Our aim is to use Fourier techniques to analyse this periodicity, and thereby to develop a tool to recognize coding regions in genomic DNA.

RESULT

The three-base periodicity in the nucleotide arrangement is evidenced as a sharp peak at frequency f = 1/3 in the Fourier (or power) spectrum. From extensive spectral analysis of DNA sequences of total length over 5.5 million base pairs from a wide variety or organisms (including the human genome), and by separately examining coding and non-coding sequences, we find that the relative-height of the peak at f = 1/3 in the Fourier spectrum is a good discriminator of coding potential. This feature is utilized by us to detect probable coding regions in DNA sequences, by examining the local signal-to-noise ratio of the peak within a sliding window. While the overall accuracy is comparable to that of other techniques currently in use, the measure that is presently proposed is independent of training sets or existing database information, and can thus find general application.

AVAILABILITY

A computer program GeneScan which locates coding open reading frames and exonic regions in genomic sequences has been developed, and is available on request.

Influence of working electrodes in Belousov–Zhabotinsky oscillatory system

The potential oscillatory profiles recorded simultaneously in the same B–Z system using platinum, glassy carbon, and graphite electrodes are different in their characteristics. The variance in the amplitude and potential range is a result of the difference in the potential response of the electrode to the different redox couples. The results obtained by employing cyanoacetic acid, syringic acid, malonic acid, citric acid, methylacetoacetate, or vanillin as the substrate and Ce(III), Mn(II), or Ferroin as the catalyst are presented. The response of the working electrode to the various redox couples is correlated to the value of the exchange current density. Keywords: potential oscillatory profile, redox couple, working electrode, potential response, exchange current density.

Prognostic criteria in Clostridium difficile colitis

OBJECTIVE

To determine the prognostic factors in Clostridium difficile (CD) colitis.

METHODS

We conducted a retrospective study of proven cases of CD colitis in l8 months. Seventy six patients (from a 605-bed community hospital in the Bronx, NY) with proven CD colitis were studied. Mortality in patients with CD colitis was also examined.

RESULTS

Seventy six patients with proven CD colitis were admitted between January 1993 and June 1994. Eighteen patients died during the same admission. Upon admission, serum albumin was less than 25 g/L in 12 (20.6%) of the survivors and in eight (44%) of the deceased patients (p <0.05). A fall in serum albumin levels was noted with the onset of symptoms of CD colitis in those who survived as well as in those who died, with a greater fall of 11.2 g/L (range 10-20 g/L) in patients who died compared with a fall of 6 g/L (range 5-10 g/L)in those who survived (p <0.05). Use of more than three antibiotics was noted in 13 (72%) of those who died and in 18 (31%) of those who survived (p <0.05). Persistence of CD cytotoxin 7 or more days after initiation of treatment was present in 14 (77%) of those who died and in eight (13%) of the survivors (p <0.01). Duration of hospitalization correlated with the development of CD colitis (35.89 vs 11.7 days) with no significant difference between survivors and deceased patients with CD colitis. Factors such as age, sex, residence, past medical history score, mean score of presenting complaints of CD colitis, history of prior episodes CD colitis, and mean number of recurrent episodes showed no difference in mortality.

CONCLUSION

Factors predictive of an increased mortality in patients with CD colitis include a serum albumin of less than 25 g/L on admission, a fall in serum albumin level of greater than 11 g/L at the onset of symptoms of CD colitis, use of three or more antibiotics, and persistence of positive CD cytotoxin in the stool after completion of 7 or more days of treatment.

Novel experimental findings in the B–Z system employing mixed substrates

Certain novel features of the Belousov–Zhabotinsky (B–Z) system employing different mixed substrates and Mn(II) as the catalyst are presented. Malic acid is the common substrate together with one of malonic, citric, cyanoacetic, maleic, acetic, oxalic, or tartaric acid as the second substrate. The correlation of the oscillatory behaviour with values of exchange current density establishes the oscillatory control by the redox couple, namely, Mn(III)/Mn(II) and (or) Br2/Br−. Each substrate when used alone gives rise to an oscillatory behaviour with characteristic features that can be compared with the system containing mixed substrate. The combination of substrates provides different modes of oscillatory behaviour such as entrainment, independent, partial inhibition, or complete inhibition. These observations are rationalized in terms of relevant steps involved in the mechanism of the reaction. Key words: mixed substrate, exchange current density, entrainment, independent, inhibition.